Environmental Engineering Reference
In-Depth Information
to October. After the harbour breakwater was completed in 1954 it acted as a trap
for beach sand drifting southward each winter, and prevented it from being car-
ried back by south-westerly waves in the summer months. By 1960, little beach
sand was left on the Hampton coast, much of it having drifted into the lee of the
Sandringham Harbour breakwater to accumulate as a wide prograded sandy plain
(Bird
1996
). This reduced the area of the harbour, which was also shallowed by
sand deposition.
Depletion of the beach between Green Point and Hampton left the sea wall
exposed to damage by storm waves, and the Victorian Division of Ports and
Harbors then decided to renourish the northern part of the beach. In order to pre-
vent sand drifting south in the winter months into Sandringham Harbour it was
necessary to construct a boulder groyne 160 m long in the middle of Hampton
Bay at an angle of 65° to the coastline, so that the emplaced beach was exposed to
south-westerly wave action, which could drive the accumulated sand back north-
ward in summer. Early in 1987 108,000 m
3
of coarse sand was dredged from an
area 2 km offshore and piped into form a beach 40 m wide and 1,100 m long,
extending from this groyne north to Green Point, known as South Brighton beach
(Fig.
4.28
); it was initially formed as a terrace 2 m above low spring tide level, the
top of the groyne being 0.3 m higher.
In the winter of 1987 some of the sand was washed southward over the groyne
(Fig.
4.28
), and in the following summer the beach towards Green Point was wid-
ened by northward drift, with some sand moving past this headland. Over the next
few years this sequence was repeated, and successive spits were built out north
from Green Point in summer, pushed back by storm waves in the following winter
Fig. 4.28
At Brighton on the NE coast of Port Phillip Bay an artificial beach was inserted
between Green Point and a groyne constructed at New Street in 1987 (
a
). Some of the sand
was washed southward over the groyne (
b
) during the following winter, and some drifted round
Green Point to form a spit to the north (
c
) in the following summer. © Geostudies
